Expansion wire

Abstract

To provide an expansion wire that solves problems of noise, biting into a machine, and deterioration of cover of a conductor wire accompanying robot arm extension / contraction, which may be caused particularly in using with a robot arm.SOLUTION: The problem is a stretchable electric wire consisting of a first conductive wire, a second conductive wire, and a knit fabric, with the first conductive wire being held on one side of the knit fabric and the second conductive wire being held on the other side. The first and second conductive wires are formed as continuous waveforms in a predetermined direction, and the positions of the waveforms of the first and second conductive wires are offset by half a wavelength in the predetermined direction, thereby the problem is resolved.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an expandable electric cord comprising a first conductive wire, a second conductive wire, and a knitted fabric that holds them. [Background technology]

[0002] Conductive wires that are stretchable in a specific direction and conductive, known as expandable electric wires, have been used as wiring in a variety of fields, including office automation equipment and industrial machinery.

[0003] For example, Patent Document 1 discloses an expandable electric cord consisting of a plurality of conductive wires 10 extending in a predetermined direction, fibers 20 into which the conductive wires 10 are woven, and a knitted fabric 30 that holds the conductive wires 10 with the fibers 20. In this expandable electric cord, the plurality of conductive wires 10 each have a waveform that oscillates in a direction Y perpendicular to the predetermined direction X, and these waveforms are each connected in the predetermined direction X to form an expandable electric cord extending in the predetermined direction X. This allows the electric cord of Patent Document 1 to have expandability in both the longitudinal direction and the direction perpendicular to the longitudinal direction.

[0004] However, when attempting to use such expandable electric wires in certain fields of industrial machinery, particularly in robot arms, it has been found that a number of problems arise, as will be explained below.

[0005] The first problem is that of the effects of noise. Robot arms use many electronic components that are electronically controlled to function. When a signal current is passed through the expandable wire, a magnetic field is generated, and depending on the arrangement of the wires, these magnetic fields can reinforce each other and become a source of noise. Depending on the noise generated, it may have an adverse effect on the control of the robot arm, and ultimately cause the robot arm to malfunction.

[0006] In addition, a robot arm operates by extending and bending the arm, but if the wiring is attached to the outside of the arm, and the wiring becomes loose when the arm is bent, depending on its placement, the loosened wiring may get inside the structure of the robot arm, causing a problem known as pinching. To prevent such pinching, it is possible to place the expandable electric wire in the robot arm in a state where it is already stretched to a certain extent, but this would require more output and power to operate the arm, making it inefficient. It is also possible to place the wiring inside the arm, but this would make the structure complicated, especially in the rotating parts, and would also put excessive load on the bending parts, creating a risk of wire breakage.

[0007] Furthermore, since the arm of the robot arm is repeatedly extended and bent a considerable number of times, the expandable electric wire is expanded and contracted accordingly a considerable number of times. During expansion and contraction, the conductive wire, particularly the coating of the conductive wire, may deteriorate, which may cause problems such as a short circuit. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2016-092009 A Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide an expandable electric cord that solves the above-mentioned problems in the conventional technology. [Means for solving the problem]

[0010] This problem is solved by an expandable electric cord consisting of a first conductive wire, a second conductive wire, and a knitted fabric, in which the first conductive wire is held on one side of the knitted fabric and the second conductive wire is held on the other side, the first conductive wire and the second conductive wire are formed as a continuous waveform in a predetermined direction, and the first conductive wire and the second conductive wire are arranged such that the waveform positions of the first conductive wire and the second conductive wire are shifted by half a wavelength in the predetermined direction.

[0011] In a preferred embodiment of the present invention, the knitted fabric is formed as an elastic and / or insulating fabric, so that even if the coating of the conductive wire deteriorates when the expandable electric wire is repeatedly expanded and contracted, the knitted fabric itself functions as an insulator, and problems caused by short circuits between the signal electric wires are avoided.

[0012] In a further preferred development of the present invention, the waveform of the first conductive wire and the waveform of the second conductive wire are formed substantially symmetrically with respect to a virtual straight line on the knitted fabric, and the waveform position of the first conductive wire and the waveform position of the second conductive wire are arranged to be shifted from each other by half a wavelength, and a part of the waveform of the first conductive wire extends beyond the straight line and reaches the loop of the second conductive wire, so that when the knitted fabric is folded along the straight line, the waveform position of the first conductive wire and the waveform position of the second conductive wire are shifted from each other by half a wavelength on the surfaces of the knitted fabric that do not contact each other. This makes it possible for the expandable electric cord to prevent noise generation not only on the surfaces of the knitted fabric that do not contact each other, but also on the folded surface. [Brief description of the drawings]

[0013] [Figure 1] Schematic diagram of the expandable electric wire according to the present invention [Diagram 2] A diagram of magnetic fields and noise generated in a typical electric wire [Diagram 3] FIG. 1 is a diagram for explaining the principle of avoiding magnetic field and noise generation in the expandable electric wire according to the present invention. [Figure 4]FIG. 1 is a diagram of an embodiment of an expandable electric wire according to the present invention. [Diagram 5] FIG. 4 is a diagram showing one embodiment of the expandable electric wire according to the present invention (a diagram showing the embodiment of FIG. 4 from the back). [Figure 6] FIG. 1 is a diagram of another embodiment of the expandable electric cord according to the present invention. [Figure 7] FIG. 1 is a partially enlarged view of a manufacturing device for an expandable electric wire according to the present invention and a diagram showing the manufacturing principle. [Figure 8] FIG. 1 is a diagram of another embodiment of the expandable electric cord according to the present invention. [Figure 9] FIG. 2 is a diagram of a manufacturing method according to another embodiment of the present invention. [Figure 10] FIG. 7 is a view of another embodiment of the expandable electric cord according to the present invention, as seen from the direction of the arrow in FIG. [Figure 11] FIG. 1 is a diagram showing a method of using the expandable electric wire according to the present invention in a robot arm. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will now be described in detail with reference to the accompanying drawings.

[0015] Fig. 1 is a schematic diagram of an expandable electric wire according to the present invention. Fig. 1a shows a top view (front view) of the expandable electric wire according to the present invention, and Fig. 1b shows a cross-sectional view of the expandable electric wire according to the present invention.

[0016] As shown in Fig. 1, the expandable electric cord according to the present invention comprises a first conductive wire 10 and a second conductive wire 20 for passing a signal current, and a knitted fabric 30 for holding the first and second conductive wires. As can be seen in Fig. 1b, the knitted fabric 30 holds the first conductive wire 10 on one side (the upper side in Fig. 1b) and the second conductive wire 20 on the other side (the lower side in Fig. 1b). In other words, the knitted fabric 30 holds the first conductive wire 10 and the second conductive wire 20 on both sides, respectively. For this reason, in Fig. 1a, the second conductive wire 20 held on the lower side of the knitted fabric 30 is drawn with a dashed line.

[0017] The first conductive wire 10 and the second conductive wire 20 each may have one or more conductive wires therein, the outer circumference of which is covered with an insulating coating, and may be generally conductive, and may not themselves have elasticity. The first conductive wire 10 and the second conductive wire 20 may also have a structure in which multiple conductive threads are twisted together, the core of which is conductive and the periphery of which is covered with an insulating coating.

[0018] The knitted fabric 30 is formed as a fabric woven from insulating and / or elastic fibers, and as a result, the formed knitted fabric 30 as a whole has insulating and / or elastic properties. Although typical fibers in thread form do not have elasticity, it is possible to make the fiber elastic by using rubber thread made of polyurethane, for example.

[0019] As can be seen in Fig. 1, the first and second conductive wires 10, 20 are each formed into a corrugated shape. In this embodiment, the corrugation is formed continuously in one direction X with a constant period, a constant wavelength, and a constant amplitude. The first conductive wire 10 and the second conductive wire 20 are held on both sides of the knitted fabric 30 so that their corrugations are shifted in phase with each other by a half wavelength. As a result, the positional relationship of the corrugations of the first conductive wire 10 and the second conductive wire 20 is formed as shown in Fig. 1a.

[0020] Here, the generation of a magnetic field and noise in a signal wire and the principle of preventing noise generation in the expandable electric wire according to the present invention will be described with reference to Figs.

[0021] Figure 2 shows how a magnetic field is generated in a typical signal cable with two conductors arranged parallel to each other. When signal currents are passed in opposite directions in the state shown in Figure 2, the magnetic field generated follows the right-hand rule: in the upper conductor in Figure 2, the magnetic field is generated counterclockwise from the front to the back of the figure, and in the lower conductor, the magnetic field is generated clockwise from the back to the front of the figure. As a result, in the area between the two conductors, the magnetic fields generated by both conductors are added together from the back to the front of the figure, creating a source of noise.

[0022] In contrast, Fig. 3 shows the arrangement of two conductive wires in the expandable electric cord according to the present invention and the principle of preventing noise generation thereby. In the expandable electric cord according to the present invention, the two conductive wires are each formed into a waveform, and these conductive wires are arranged and held at positions where the phases of the waveforms are shifted by half a wavelength. Therefore, when signal currents are passed through the conductive wires in opposite directions, for example, the magnetic field in region A in Fig. 3 is generated from the front to the back of the figure in the left part of Fig. 3, and is generated from the back to the front of the figure in the right part, so that the magnetic fields in adjacent parts have opposite directions and cancel each other out. This prevents noise generation.

[0023] In this way, the knitted fabric 30 is formed as an elastic knitted fabric, the electric wire held therein is formed as an electric wire having a continuous waveform in a predetermined direction on both sides of the knitted fabric 30, and the electric wires held on both sides of the knitted fabric 30 are arranged at positions where the phases of the waveforms formed by both electric wires are shifted from each other by half a wavelength, so that the formed expandable electric wire has elasticity in a predetermined direction and the function of preventing the generation of noise.

[0024] On the other hand, if the knitted fabric 30 is formed as a non-elastic knitted fabric, the electric wires held therein are formed as electric wires having a continuous waveform in a predetermined direction on both sides of the knitted fabric 30, and the electric wires held on both sides of the knitted fabric 30 are arranged at positions where the phases of the waveforms formed by both electric wires are shifted from each other by half a wavelength, the electric wires formed can be formed as a knitted fabric, and this can be formed into a complex harness shape by a knitting machine. In this case, the total length of the electric wires used can be shortened compared to when the knitted fabric 30 having elasticity is used, so that the resistance value of the entire harness can be kept low, which is advantageous in terms of power consumption, etc.

[0025] Figures 4 and 5 show an expandable electric wire according to one embodiment of the present invention. Figure 4 shows one side (front side) of an expandable electric wire, and Figure 5 shows the other side (back side) of the same expandable electric wire. In this embodiment, three conductive wires are arranged in parallel on the front side. The left side of Figure 4 shows the expandable electric wire when kept at its free length, and the right side shows the same expandable electric wire when stretched. It can be seen that the wavelength of the conductive wire is longer in the right side compared to the left side.

[0026] Figure 5 shows the state of the other side of the expandable electric wire in Figure 4. As in Figure 4, three conductive wires are arranged in parallel on the back side of the expandable electric wire according to this embodiment. The left side of Figure 4 shows the expandable electric wire in a state where it is kept at its free length, and the right side shows the same expandable electric wire in a stretched state.

[0027] Fig. 6 shows another embodiment of the expandable electric cord according to the present invention. The embodiment in this figure differs from that in Figs. 4 and 5 in the number of conductive wires arranged. While three conductive wires are arranged on each of the front and back sides in Figs. 4 and 5, the embodiment in Fig. 6 has six conductive wires arranged on each of the front and back sides. By increasing the number of conductive wires arranged in this way, it becomes possible to pass a larger current.

[0028] Fig. 7 shows a part of the apparatus for manufacturing the expandable electric cord according to the present invention (only guide plates, eyes, needle plates, and needles) and an outline of the manufacturing method. In this embodiment, the knitted fabric used for the expandable electric cord according to the present invention is formed by warp knitting. To form such a knitted fabric, a warp knitting machine using multiple guide plates as shown in Fig. 7 is used in the present invention. In this embodiment, a warp knitting machine using five guide plates is used.

[0029] When using this warp knitting machine, the weft yarn is divided into left and right yarns with different swing widths. The guide plates (reeds) for the weft yarns used are numbered 1 to 5. Among them, the guide plates numbered 2 and 4 are used for the conductive wires (dashed lines and solid lines). The guide plates numbered 1, 3, and 5 are used for the knitted fabric 30. By forming the knitted fabric in this manner, the knitted fabric tends to be flat because it is bound by the warp yarns. In addition, the conductive wires of the completed knitted fabric are knitted fabrics that avoid the generation of knitted fabric noise (have a noise canceling function) as shown in FIG. 1 on a plane. Furthermore, when viewed in cross section, gaps that absorb noise waves are formed on both sides of the knitted fabric. Such gaps are formed by configuring the yarns of the guide plates numbered 1, 3, and 5 that constitute the base knitted fabric 30 to be above and below the conductive wires of the guide plates numbered 2 and 4, and to cross each other in cross section.

[0030] FIG. 8 shows an expandable electric cord according to another embodiment of the present invention. In this embodiment, the width of the weft thread is changed and the weft thread is divided into left and right. Guide plates numbered 1 to 3 in FIG. 6 are used as guide plates for the weft thread. Guide plates numbered 2 and 4 in FIG. 7 are used for the conductive wires. The lower half of FIG. 8 shows which guide plate of such a configuration is used for the conductive wires 10 and 20 and the knitted fabric 30 at each weaving position. That is, the guide plate numbered 4 is used for the first conductive wire 10, the guide plate numbered 2 is used for the second conductive wire 20, and the guide plate numbered 3 is used for the knitted fabric 30. By forming the expandable electric cord with such a configuration, the expandable electric cord is in the state shown in FIG. 9.

[0031] When the expandable electric wire formed in the state of FIG. 9 is bent in half at the center (line AA) of FIG. 9, the conductive wire is in the state shown in FIG. 1 in plan view, that is, in a state having the function of preventing noise generation. Furthermore, when this state is viewed from the direction of arrow B in FIG. 9 (when viewed in cross section), it is formed in the state shown in FIG. 10. In the state of FIG. 10, gaps that absorb noise waves are formed on both sides of the knitted fabric 30. This is realized by distributing and knitting the conductive wires of solid lines and dashed lines on both sides of the knitted fabric. Furthermore, each conductive wire drawn with solid lines and dashed lines is structured to form a loop by extending the conductive wire drawn with solid lines until it is caught in the loop of the conductive wire drawn with dashed lines, but in reality, these conductive wires are distributed on both sides of the knitted fabric 30 and do not come into contact with each other.

[0032] Finally, a method of using the expandable electric wire according to the present invention in an actual robot arm will be described with reference to Fig. 11. Fig. 11 shows a conceptual diagram of a state in which the expandable electric wire according to the present invention is attached to a robot arm as its signal wiring.

[0033] Fig. 11(a) shows the so-called standard or initial state of the robot arm, with the arm not bent to either the left or right. One expandable electric wire according to the present invention is attached to each of the inside and outside of the bending direction of this robot arm. When attached, each expandable electric wire is already attached in a state of 50% expansion rate (a state in which the total length is stretched by 50% from the initial state). In other words, tensile forces are acting on both the left and right sides of the arm, but these forces cancel each other out.

[0034] 11(b) shows the state in which the robot arm is bent most to the left from the standard state / initial state described above. The total length and the stretch rate of the expandable electric wire are configured so that in this state, the stretch rate of the expandable electric wire on the left side of the figure is 0% (natural length, free length state) and the stretch rate of the expandable electric wire on the right side is 100% (the total length is stretched 100% from the initial state).

[0035] 11(c) shows the state in which the robot arm is bent most to the right from the standard / initial state described above. The total length and the stretch rate of the expandable electric wire are configured so that in this state, the stretch rate of the expandable electric wire on the right side of the figure is 0% (natural length, free length state) and the stretch rate of the expandable electric wire on the left side is 100% (the total length is stretched 100% from the initial state).

[0036] In this way, by arranging the expandable electric wires on opposing surfaces of the robot arm at the center (diagonal arrangement), the forces for expanding and contracting the expandable electric wires cancel each other out, making it possible to significantly reduce the power required to operate the robot arm.

[0037] FIG. 11 shows an example in which the robot arm bends only in the left-right direction. However, if the arm bends in, for example, four directions, by arranging the expandable electric wire according to the present invention on the four diagonal corners, it is possible to reduce the power required to operate the robot arm in all directions in which the arm bends. [Explanation of symbols]

[0038] 10 First Conductive Wire 20 Second conductive wire 30 Knitting

Claims

1. An expandable electric cord comprising a first conductive wire (10), a second conductive wire (20), and a knitted fabric (30), the first conductive wire (10) being held on one surface of the knitted fabric (30) and the second conductive wire (20) being held on the other surface, the first conductive wire (10) and the second conductive wire (20) being formed as a continuous waveform in a predetermined direction (X), and the first conductive wire (10) and the second conductive wire (20) being arranged such that the waveform positions of the first conductive wire (10) and the second conductive wire (20) are shifted by a half wavelength in the predetermined direction (X).

2. The expandable electric cord according to claim 1, characterized in that the knitted material (30) is formed as a knitted fabric having elasticity and / or insulating properties.

3. an expandable electric cord, characterized in that the waveform produced by the first conductive wire (10) and the waveform produced by the second conductive wire (20) are formed in approximate line symmetry with respect to an imaginary straight line (AA) on the knitted fabric (30), the waveform position of the first conductive wire (10) and the waveform position of the second conductive wire (20) are arranged to be shifted by a half wavelength from each other, and a part of the waveform of the first conductive wire (10) extends beyond the straight line (AA) until it reaches a loop of the second conductive wire (20), so that when the knitted fabric (30) is bent about the straight line (AA), the waveform position of the first conductive wire (10) and the waveform position of the second conductive wire (20) are shifted from each other by a half wavelength.

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